ture which have been already described, are the changes of habits
which often occur in certain individuals or in whole species, since
these must necessarily depend upon some corresponding change in the
brain or in other parts of the organism; and as these changes are of
great importance in relation to the theory of instinct, a few examples
of them will be now adduced.

The Kea (Nestor notabilis) is a curious parrot inhabiting the mountain
ranges of the Middle Island of New Zealand. It belongs to the family of
Brush-tongued parrots, and naturally feeds on the honey of flowers and
the insects which frequent them, together with such fruits or berries as
are found in the region. Till quite recently this comprised its whole
diet, but since the country it inhabits has become occupied by Europeans
it has developed a taste for a carnivorous diet, with alarming results.
It began by picking the sheepskins hung out to dry or the meat in
process of being cured. About 1868 it was first observed to attack
living sheep, which had frequently been found with raw and bleeding
wounds on their backs. Since then it is stated that the bird actually
burrows into the living sheep, eating its way down to the kidneys, which
form its special delicacy. As a natural consequence, the bird is being
destroyed as rapidly as possible, and one of the rare and curious
members of the New Zealand fauna will no doubt shortly cease to exist.
The case affords a remarkable instance of how the climbing feet and
powerful hooked beak developed for one set of purposes can be applied to
another altogether different purpose, and it also shows how little real
stability there may be in what appear to us the most fixed habits of
life. A somewhat similar change of diet has been recorded by the Duke of
Argyll, in which a goose, reared by a golden eagle, was taught by its
foster-parent to eat flesh, which it continued to do regularly and
apparently with great relish.[26]

Change of habits appears to be often a result of imitation, of which Mr.
Tegetmeier gives some good examples. He states that if pigeons are
reared exclusively with small grain, as wheat or barley, they will
starve before eating beans. But when they are thus starving, if a
bean-eating pigeon is put among them, they follow its example, and
thereafter adopt the habit. So fowls sometimes refuse to eat maize, but
on seeing others eat it, they do the same and become excessively fond of
it. Many persons have fo